Live Conductor Stringing, Maintenance and Repair Method

ABSTRACT

The present invention relates to replacing conductors in a high-voltage power transfer system. The method provides, for example, a method for maintaining sections of electrically conductive phases in a three-phase power conductor line, wherein the three phases are parallel and spaced apart in an ordered sequence. The phases are strung between support structures and supported above the ground. Maintenance work, which include replacement or repair, is performed on sections of the three phases without interrupting a power load in any one of the three phases and without transposing the relative positions of the phases out of their ordered sequence.

FIELD OF THE INVENTION

The present invention relates generally to high voltage power transfersystems. In particular, the present invention relates to replacingconductors in a high voltage power transfer system.

BACKGROUND OF THE INVENTION

Users of large amounts of electrical power such as cities, manufacturingfacilities, and other high-power users are often located quite adistance away from sources of electrical power such as hydroelectricdams and power plants. In order to deliver large amounts of power fromthe source of generation to the power consumers, large, high-capacity,high-voltage power lines are used.

Typically, alternating current (“AC”) is generated in a three-phaseconfiguration. For the purposes of this document, the three phases willbe referred to as A, B and C phase. A phase, B phase and C phase are alltransported over separate conductors. In some instances direct current(DC power) is used in which case two conductors are used and arereferred to as A and C phase. Typically, the conductors are comprised oflong wires supported on large support structures such as towers or powerpoles. The separate A, B and C phase conductors are typically attachedto the same support structures on insulators.

From time to time, the power lines transporting the power may requiremaintenance. For example, a section of the conductor may need to bereplaced, an insulator insulating the power line from the supportstructure may need to be replaced, or, the support structure itself mayneed repair or replacement. In some cases, conductors may be functioningproperly, but need to be replaced by higher-capacity conductors in orderto transport more power.

Typical maintenance on power lines requires that the power be shut offbefore the line can be worked on. High induction currents may be inducedinto a conductor located in the proximity of other high voltageconductors, thus creating a hazard in order to work on a particularconductor.

Shutting off the power creates a disruption of power delivery tocustomers. A power user may be forced to do without power during thetime the power line is maintained, which is undesirable for a variety ofreasons. To provide consumers power while a particular line is beingworked on, the load may be shifted to other power lines to deliver thepower to the end user. Unfortunately, shifting power to othertransmission lines is not always possible because redundant systems maynot exist, or transmission lines may already be operating at or nearcapacity level and not able to deliver the required power.

Previously, the applicant developed methods for conducting maintenancework on energized high voltage conductors in electrical transmissionsystems, such as the methods described in the U.S. Pat. No. 7,535,132issued on May 19, 2009 to Quanta Associates, L. P. One of the methodstaught in U.S. Pat. No. 7,535,132 involves moving each of the conductorsneeding replacement to a temporary position, stringing new conductors inor near the originating positions of the old conductors, transferringthe power load from each of the old conductors to each of the newconductors using transfer buses, and removing the old conductors.

However, one problem that often occurs during the execution of themethods described in U.S. Pat. No. 7,535,132 is that the movement ofeach of the old conductors requiring replacement to temporary positionsat the same time will often result in the transposition of theconductors carrying phases A, B and C, whereby, for example, if thephases were originally arranged in the relative horizontal positions ofA— B— C prior to moving the phases to their temporary positions, therelative horizontal positions may often end up in the positions B— A— Cafter the movement has occurred. Furthermore, in order to achieve movingall three phases to temporary positions at the same time using themethods described in U.S. Pat. No. 7,535,132, it is often necessary toutilize long jumper cables to connect the temporarily relocated sectionof conductor to the remaining sections, which jumper cables for onephase must necessarily cross over the conductors of another phase whilecarrying a power load, as illustrated in FIG. 35 of U.S. Pat. No.7,535,132. These are examples of what the Applicant refers to as illegaltranspositions of the phase conductors. The disclosure of U.S. Pat. No.7,535,132 is incorporated herein in its entirety, and is hereinafterreferred to as the '132 patent.

Both scenarios described above results in the transposition of the phaseconductors, leading to an imbalance in the impedances of the phaseconductors and therefore, fluctuations in the voltage and currentcarried on the phase conductors. Such fluctuations, if large enough,will cause the protective relays to trip the breakers, causing adisruption in the delivery of power on the transmission lines beingworked upon. To avoid this result, the owner of the power transmissionline may choose to disable the safety relays while a live reconductoringproject is underway. However, disabling the safety relays results in arisk that a sudden fluctuation in the voltage and current during thelive reconductoring project may damage the transmission network.

Accordingly, it is desirable to provide an improved method to allow highvoltage power transmission lines to be worked on, replaced or maintainedwithout requiring power to stop being delivered or diverted over toother remote transmission lines, and without resulting in the illegaltransposition of the phase conductors that could lead to faults in thetransmission line.

SUMMARY

One example embodiment of the present invention provides a method formaintaining a section of an electrified, three-phase power conductorline, wherein the three phases are in a common plane, in an orderedsequence and strung between a set of support structures, wherein atleast two equal potential zones are employed in communication with atleast one of said three phases, the method comprising steps of:

-   a) positioning at least one auxiliary support substantially adjacent    the set of support structures so as to support an electrified    section of a first phase-needing-maintenance,-   b) moving said section of said first phase-needing-maintenance so as    to be strung upon said at least one auxiliary support and said at    least two auxiliary dead end supports, wherein said first and second    dead end junctures are supported by said at least two auxiliary dead    end supports,-   c) stringing a first new phase conductor between the set of support    structures where the section was moved from,-   d) electrically connecting a first transfer bus and a second    transfer bus to said first new phase conductor,-   e) electrically connecting said second conductor of said first    transfer bus and said second conductor of said second transfer bus    to a second phase section of a second phase-needing-maintenance that    is proximate to said first phase-needing-maintenance, wherein said    second phase section comprises a third dead end juncture and a    fourth dead end juncture,-   f) electrically connecting said first transfer bus so as to bring    said first new phase conductor to an electrical potential that is    equal to said second phase-needing maintenance,-   g) completing a first electrically parallel connection between said    first new phase conductor and said second phase-needing-maintenance,-   h) electrically connecting said new phase conductor to a first    segment of said second phase-needing-maintenance on opposite sides    of said third dead end juncture, and electrically connecting said    first new phase conductor to a second segment of said second    phase-needing-maintenance on opposite sides of said fourth dead end    juncture, so as to complete a second electrically parallel    connection between said first new phase conductor and said second    phase-needing-maintenance,-   i) electrically disconnecting said section of said second    phase-needing-maintenance so as to isolate said second phase section    of said second phase-needing-maintenance from said first and second    segments of said second phase-needing-maintenance and said first new    phase conductor, and-   j) maintaining said second phase section of said second    phase-needing-maintenance.

Another example embodiment of the present invention provides a methodfor maintaining sections of electrically conductive phases in a threephase power conductor line, the three phases denoted as the A, B and Cphases, wherein the three phases are parallel and spaced apart in anordered sequence wherein the A phase is proximate to the B phase and theB phase is proximate to the C phase, but the A phase is not proximate tothe C phase, and wherein the A, B and C phases are strung betweensupport structures supporting the three phases suspended above a ground,and wherein maintenance work is performed on sections of the threephases without interruption of a power load in any one of the threephases and without transposing the relative positions of the A, B and Cphases out of their ordered sequence, wherein at least two equalpotential zones are employed in communication with at least one of saidA, B and C phases.

Another example embodiment of the present invention provides a method ofmaintaining sections of electrically energized phases in a three phasepower conductor line, the three phases being an A phase, a B phase and aC phase, the method comprising:

-   a) providing, between two support structures above a ground surface,    the A phase is proximate to the B phase, the B phase is proximate to    the C phase and the B phase is located between the A phase and the C    phase with the phases all in a common plane;-   b) without interrupting an alternating current power of the A phase,    the B phase and the C phase, performing maintenance work on sections    of the A phase, the B phase and the C phase;-   c) without interrupting an alternating current power of the A phase,    the B phase and the C phase, non-transposing the relative positions    of the A phase, the B phase and the C phase; and,-   d) employing at least two equal potential zones in conjunction with    at least one of said A phase, B phase and C phase.

As described in the '132 patent entitled Live Conductor Stringing andSplicing Method and Apparatus, the disclosure of which is incorporatedherein by reference in its entirety, a person ordinarily skilled in theart will readily understand how to employ the aforementioned stringingmethod described above, including the construction of equal potentialzones, the use of hot line tools and live line work methods that aredescribed in the '132 patent specification. In particular, see FIGS. 57through 98 and column 22, line 48 through column 33, line 60 of patent′132.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a power transfer system fortransferring power in three electrical phases, one electrical phasebeing transferred per conductor.

FIG. 2 is a side view of a support structure for a power transfer systemshowing a temporary support structure located proximate to a permanentsupport structure configured for the temporary relocation of a phaseconductor at a distance substantially equal to the phase spacing betweenthe other phase conductors.

FIG. 3 is a schematic diagram illustrating the power transfer system ofFIG. 1 showing temporary support structures added in accordance with theinvention.

FIG. 4 is a side view of the support structure of FIG. 2 , illustratingthe relocation of a phase conductor from its permanent support structureto a temporary location on a temporary support structure.

FIG. 5 is a schematic diagram illustrating the power transfer system ofFIG. 3 showing the relocation of a phase conductor to a temporarylocation on temporary support structures.

FIG. 6 is a schematic diagram illustrating the power transfer system ofFIG. 5 showing the relocation of a first dead end to a temporarylocation.

FIG. 7 is a schematic diagram illustrating the power transfer system ofFIG. 6 showing the relocation of a second dead end to a temporarylocation.

FIG. 8 is a schematic diagram illustrating the power transfer system ofFIG. 7 showing new conductor installed between new dead end structures.

FIG. 9 is a schematic diagram illustrating the power transfer system ofFIG. 8 showing a first temporary transfer bus partially installed.

FIG. 9A is a detail view of a portion of the schematic diagramillustrating the power transfer system of FIG. 9 showing the electricalconnection between a first temporary transfer bus and a phase conductor.

FIG. 10 is a schematic diagram illustrating the power transfer system ofFIG. 9 showing a second temporary transfer bus partially installed.

FIG. 11 is a schematic diagram illustrating the power transfer system ofFIG. 10 showing the first temporary transfer bus fully installed.

FIG. 12 is a schematic diagram illustrating the power transfer system ofFIG. 11 showing the second temporary transfer bus fully installed.

FIG. 13 is a schematic diagram illustrating the power transfer system ofFIG. 12 showing a new conductor electrically connected to the B phaseconductor across the second transfer bus that is connected to a closedbreaker.

FIG. 14 is a schematic diagram illustrating the power transfer system ofFIG. 13 showing a new conductor connected in parallel to the B phaseconductor across two transfer buses that are each connected to a closedbreaker.

FIG. 15 is a schematic diagram illustrating the power transfer system ofFIG. 14 showing a jumper cable connecting the original B phase conductorto the new phase conductor across a dead end on the B phase conductorand a dead end located between the original A phase conductor and thenew conductor.

FIG. 16 is a schematic diagram illustrating the power transfer system ofFIG. 15 showing two jumper cables removed from around a dead end on theB phase conductor.

FIG. 17 is a schematic diagram illustrating the power transfer system ofFIG. 16 showing a jumper cable connecting the original B phase conductorto the new phase conductor across a dead end on the B phase conductorand a dead end located between the original A phase conductor and thenew conductor.

FIG. 18 is a schematic diagram illustrating the power transfer system ofFIG. 17 showing two jumper cables removed from around a dead end on theB phase conductor.

FIG. 19 is a schematic diagram illustrating the power transfer system ofFIG. 18 showing the breaker connected to the first temporary transferbus set to the open position and breaking parallel between the newconductor and the original B phase conductor.

FIG. 20 is a schematic diagram illustrating the power transfer system ofFIG. 19 showing the breaker connected to the second temporary transferbus set to the open position and breaking the electrical connectionbetween the new conductor and the original B phase conductor.

FIG. 21 is a schematic diagram illustrating the power transfer system ofFIG. 20 showing the second transfer bus disconnected from the breakerand removed from the power transfer system.

FIG. 22 is a schematic diagram illustrating the power transfer system ofFIG. 21 showing the first transfer bus disconnected from the breaker andremoved from the power transfer system.

FIG. 23 is a schematic diagram illustrating the power transfer system ofFIG. 22 showing new conductor installed between dead end structures onthe original B phase conductor line.

FIG. 24 is a schematic diagram illustrating the power transfer system ofFIG. 23 showing a first and second temporary transfer bus installedbetween the C phase conductor and the new D phase conductor wherein thetwo temporary transfer buses are each connected to an open breaker.

FIG. 25 is a schematic diagram illustrating the power transfer system ofFIG. 24 showing the new conductor connected in parallel to the C phaseconductor across two transfer buses that are each connected to a closedbreaker.

FIG. 26 is a schematic diagram illustrating the power transfer system ofFIG. 25 showing two jumper cables each connecting the original C phaseconductor to the new phase conductor across dead end junctures on the Cphase conductor and dead end junctures located between the original Bphase conductor and the new conductor and the jumper cables surroundingthe two dead end junctures on the original C phase conductor removed.

FIG. 27 is a schematic diagram illustrating the power transfer system ofFIG. 26 showing the two breakers each connected to a temporary transferbus set to an open position breaking parallel between the original Cphase conductor and the new conductor.

FIG. 28 is a schematic diagram illustrating the power transfer system ofFIG. 27 showing new conductor installed between dead end structures onthe original C phase line and the two temporary transfer buses removedfrom the power transfer system.

FIG. 29 is a schematic diagram illustrating the power transfer system ofFIG. 28 showing two temporary transfer buses each connected to a breakerset in the open position and installed between the new D phase conductorand the new C phase conductor.

FIG. 30 is a schematic diagram illustrating the power transfer system ofFIG. 29 showing the new D phase conductor connected in parallel to thenew C phase conductor across two temporary transfer buses that are eachconnected to a closed breaker.

FIG. 31 is a schematic diagram illustrating the power transfer system ofFIG. 30 showing the removal of the two jumper cables illustrated in FIG.30 each connecting the original C phase conductor to the new C phaseconductor across dead end junctures and showing the installation of newjumper cables across the two dead end junctures on the new C phaseconductor line.

FIG. 32 is a schematic diagram illustrating the power transfer system ofFIG. 31 showing each of the two breakers connected to the two temporarytransfer buses set to an open position breaking parallel between the newC phase conductor and the D phase conductor.

FIG. 33 is a schematic diagram illustrating the power transfer system ofFIG. 32 showing two temporary transfer buses each connected to a breakerset in the open position and installed between the D phase conductor andthe new B phase conductor.

FIG. 34 is a schematic diagram illustrating the power transfer system ofFIG. 33 showing the D phase conductor connected in parallel to the new Bphase conductor across two temporary transfer buses that are eachconnected to a closed breaker.

FIG. 35 is a schematic diagram illustrating the power transfer system ofFIG. 34 showing the removal of the two jumper cables illustrated in FIG.34 each connecting the original B phase conductor to the new phaseconductor across dead end junctures and showing the installation of newjumper cables across the two dead end junctures on the new B phaseconductor line.

FIG. 36 is a schematic diagram illustrating the power transfer system ofFIG. 35 showing each of the two breakers connected to the two temporarytransfer buses set to an open position breaking parallel between the newB phase conductor and the D phase conductor.

FIG. 37 is a schematic diagram illustrating the power transfer system ofFIG. 36 showing two temporary transfer buses each connected to a breakerset in the open position and installed between the D phase conductor andthe original A phase conductor located in a temporary position.

FIG. 38 is a schematic diagram illustrating the power transfer system ofFIG. 37 showing the D phase conductor connected in parallel to theoriginal A phase conductor across two temporary transfer buses that areeach connected to a closed breaker.

FIG. 39 is a schematic diagram illustrating the power transfer system ofFIG. 38 showing the removal of the two jumper cables illustrated in FIG.38 each connecting the original A phase conductor to the temporarilyrelocated section of A phase conductor across dead end junctures andshowing the installation of new jumper cables across the two dead endjunctures on the new A phase conductor line.

FIG. 40 is a schematic diagram illustrating the power transfer system ofFIG. 39 showing each of the two breakers connected to the two temporarytransfer buses set to an open position breaking parallel between the newA phase conductor and the original A phase conductor.

FIG. 41 is a schematic diagram illustrating the power transfer system ofFIG. 40 showing the removal of the two temporary transfer buses and thetwo breakers from the power transfer system.

FIG. 42 is a schematic diagram illustrating the power transfer system ofFIG. 41 showing the removal of the de-energized original A phaseconductor from the power transfer system.

FIG. 43 is a side view of a temporary transfer bus suspended from twotangent insulators each supported on a phase conductor and connected toa closed breaker with jumper cables.

FIG. 44 is a top view of an air break switch in a closed position.

FIG. 45 is a top view of an air break switch in an opened position.

FIG. 46 is a side view of a portable breaker in accordance with oneembodiment of the invention.

FIG. 47 is a side view of a support structure for a power transfersystem showing a temporary support structure attached to a permanentsupport structure and insulators configured to carry double conductors(two conductors per phase).

FIG. 48 is a side view of a temporary transfer bus suspended from twotangent insulators each supported on a phase conductor and the two rigidconductors of the transfer bus electrically connected to each other by ajumper cable.

FIG. 49 is a front elevation view of a support structure for a powertransfer system showing three adjacent phases A, B and C.

FIG. 50 depicts the addition of a temporary support structure, atransfer of the C phase conductor to the temporary support structure andthe stringing of a first replacement conductor where the C phase wasmoved from.

FIG. 51 depicts the transfer of the electrical load from the B phase tothe first replacement conductor (D phase) and the stringing of a secondreplacement conductor where the B phase was located.

FIG. 52 depicts the transfer of the electrical load from the A phase tothe second replacement conductor (the new conductor strung in FIG. 51 )and the stringing of a third replacement conductor where the A phase waslocated.

FIG. 53 depicts the transfer of the electrical load from the secondreplacement conductor to the third replacement conductor.

FIG. 54 depicts the transfer of the electrical load from the firstreplacement conductor to the second replacement conductor.

FIG. 55 depicts the transfer of the electrical load from the C phaseconductor to the first replacement conductor.

FIG. 56 depicts the three replacement conductors each carrying the threephases A, B and C in the ordered sequence of FIG. 49 , the temporarysupport structure and the original C phase having been removed.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The invention will now be described with reference to the Figures, inwhich like reference numerals refer to like parts throughout. Anembodiment in accordance with one aspect of the present inventionprovides an improved method for replacing high-voltage powertransmission conductors without affecting power users or powersuppliers. The method avoids a requirement of having the powertransmitted by the conductors shut off or diverted to other remote powertransmissions systems. The method also avoids an illegal transpositionof the phase conductors when transferring the power loads from a phaseconductor to a proximate phase conductor during the maintenance orrepair work, which illegal transposition may otherwise lead to faults inthe transmission line.

As stated above, power delivery systems such as high voltage power linesoften transport Alternating Current (“AC”) power in a three phaseconfiguration. Direct Current (“DC”) power systems transfer power overtwo phases. Each phase is transferred over a separate conductor. For thepurposes of this specification, each of the letters A, B, and C willrepresent one of three phases of a three-phase AC system. The methodsand apparatus described herein can be adapted for use in a DC system byapplying the methods and apparatus described herein for the A and Bphases for the two phases of a DC system and where reference is made,for example in the claims, to the A, B and C phases, such references areintended to include merely the A and B phases for a DC implementation.Systems carrying voltages of 44 kV or higher are contemplated in theembodiments of the present invention.

In addition, throughout this specification there is often reference to afourth phase conductor, referred to as the “D phase” conductor. The Dphase conductor, as that term is used in this specification, denotes asection of a phase conductor that is not electrically connected to anyof the phase conductors that are carrying the A, B or C phases. In otherwords, the D phase is not carrying the current of any of the A, B, or Cphases. Throughout the Figures illustrating examples of embodiments ofthe present invention, a phase conductor labelled as the “D phase”conductor in one figure may be labelled as an A, B or C phase conductorin the next Figure, where the “D phase” conductor becomes electricallyconnected to another phase conductor carrying the A, B or C phasecurrent. For example, see FIGS. 12 and 13 , wherein the “D phase”conductor 114 in FIG. 12 becomes a “B phase” conductor 114 in FIG. 13 ,upon establishing an electrical connection between the conductor 114 andthe original B phase conductor 102 (B) when the breaker 142 connected tothe second transfer bus 118″ is closed. In each Figure of thisspecification, a phase conductor is either labelled “D phase”, when itis electrically isolated from any other phase conductors in the powertransfer system 100, or it is labelled “A phase”, “B phase” or “C phase”when the phase conductor is carrying the A, B or C phase current, or isotherwise electrically connected to a phase conductor that carrieseither the A, B or C phase current.

In an embodiment of the invention, a section of a first conductorlocated between two dead end junctures is moved to a temporary positionon temporary support structures. The dead end junctures of the sectionof the first conductor are also transferred to the temporary positionson the temporary support structures. A new conductor is then strung inor near the old conductor's originating position, and the power loadfrom a first proximate phase-needing-maintenance is transferred to thenew conductor. Once the power load from the first proximatephase-needing-maintenance is transferred to the new conductor, a sectionof the old conductor of the first proximate phase-needing-maintenance isremoved and replaced with a second new conductor. Once the second newconductor is in place, the power load of a second proximatephase-needing-maintenance is transferred to the second new conductor,enabling work to be conducted on a section of the second proximatephase-needing-maintenance conductor. This procedure is repeated untilall of the proximate phase conductors requiring maintenance work havehad their power loads transferred to other phase conductors. Once all ofthe maintenance work is complete, the power loads of each phase areconsecutively transferred to the phase conductors strung into thepositions where each phase was originally carried. This procedureprovides for maintenance work to be conducted on high voltagetransmission lines, without having to interrupt the supply of power tousers and avoiding the illegal transposition of the respective phaseconductors during the transfer of the power load from one phaseconductor to an adjacent phase conductor.

FIGS. 1 through 43 generally show, in schematic diagrams, a powertransfer system 100 undergoing consecutive stages of a method inaccordance with an embodiment of the invention, so that a section of aphase conductor to be worked on may be electrically isolated from thesystem power. As used herein, the term “maintenance work” includes thereplacement of the phase conductor, and may also include maintenance ofthe conductor, replacement of insulators, resagging of the conductor,all without disrupting the transmission of power to downstream powercustomers.

In many instances there may be miles between dead end junctures. If thedistance between the dead end junctures for a particular section ofphase conductor to be worked upon is too great for pulling newconductors through the system 100, then new or temporary dead endjunctures may be constructed as described later herein.

The temporary relocation of a phase conductor, the stringing of newphase conductor in a position at or near the originating position of thephase conductor, and the process of successively transferring the powerload from an adjacent phase to the new conductor such that the nextphase may be isolated and worked upon, will now be described withreference to FIGS. 1-43 .

FIG. 1 is a schematic diagram for power transfer system 100. The powertransfer system 100 includes three conductors 102, labeled A phase, Bphase and C phase, indicating that each of the conductors 102 carriesone of the A, B, or C phase load. The system 100 transfers power in theform of AC, although this is not intended to be limiting as the methoddescribed herein may be used for DC power systems. The conductors 102are supported by support structures 104. Each support structure 104 mayinclude or be in the form of a power pole or a tower. One example of asupport structure 104, not intended to be limiting, is seen in FIG. 2 .Other support structures are seen in FIGS. 53, 55 and 56 of the '132patent. A conductor 102 is attached to dead end support structures 103via insulators in tension 106 (hereinafter insulators 106). As seen inFIG. 1 , dead end junctures 110′, 110″ are formed by a pair ofinsulators 106 when in-line with conductors 102 and under tension withconductors 102. Jumper cables 108, as shown in FIG. 1 , electricallyconnect conductors 102 around insulators 106 and dead end supportstructures 103 to an oppositely disposed section of conductors 102.

Another way conductor 102 may be supported by support structure 104 isshown for example in FIG. 2 . The conductor 102 hangs from tangentinsulator 116. Tangent insulator 116 is supporting both the conductortension and the weight of conductor 102. When the weight of conductor102 is being supported by tangent insulator 116, jumper cables 108 arenot required.

In some embodiments of the present invention, a temporary supportstructure (otherwise referred to as an auxiliary support) 112 isconstructed near the location of an existing support structure 104, asshown in FIGS. 2 and 3 . The temporary support structure 112 ispreferably located near or adjacent the location of an existing supportstructure 104, whereby the distance L between the original location 95and the temporary location 96 of the A phase conductor 102 issubstantially equivalent to the phase spacing J between phases A and Band between phases B and C, when those phase conductors, 102 (A), 102(B) and 102 (C) respectively, are suspended on the existing supportstructure 104. The temporary support structure 112 may be locatedadjacent the existing support structure 104, or in the alternative thetemporary support structure 112 may be connected to the supportstructure 104 as shown in FIG. 54 in the '132 patent, for example.

Once the temporary support structures 112 are in place, a section 87 ofthe A phase conductor 102 (A) located between dead end junctures 110′and 110″ is removed from the original location 95 on the existingsupport structures 104 and transferred to the temporary position 96 onthe temporary support structure 112. FIG. 4 shows the transfer of the Aphase conductor 102 (A) from its original location 95 on supportstructure 104 to the temporary location 96 on temporary supportstructure 112, using a robotic mechanical arm device 101, such as theRemote Manipulator for Manipulating Multiple Sub-conductors in a SinglePhase Bundle described in the Applicant's U.S. Pat. No. 8,573,562, orsimilar robotic mechanical arm device adapted to manipulate heavyenergized conductors such as the A phase conductor 102 (A).

As seen in FIG. 5 , although there are only two temporary supportstructures 112, it will be appreciated by a person ordinarily skilled inthe art that a section of phase conductor 102 to be replaced may besupported by numerous support structures 104 and that more than twotemporary support structures 112 may be required to support the sectionof the phase conductor 102 that needs to be transferred to a temporarylocation 96. Furthermore, it will be appreciated by a person skilled inthe art that a section of a different phase conductor, such as a sectionof the C phase conductor 102 (C) illustrated in FIG. 3 , mayalternatively be moved to a temporary position 96 adjacent theoriginating position 95 of conductor 102 (C) in accordance with theprocedure described above with respect to conductor 102 (A) and thatsuch procedure would be within the scope of the present inventiondescribed herein.

As illustrated in FIGS. 6 and 7 , once the section 87 of phase conductor102 (A) that is the subject of maintenance work has been moved totemporary support structures 112, each of the dead end junctures 110′,110″ at either end of the section 87 of phase conductor 102 (A) aretransferred to temporary dead end poles (otherwise referred to asauxiliary dead end supports) 113′, 113″. It will be readily understoodby a person ordinarily skilled in the art, having read thisspecification, that although two temporary support structures 112, 112are illustrated in FIG. 7 , that it is possible to carry out theprocedure described herein utilizing a single temporary supportstructure 112, or otherwise to utilize more than two temporary supportstructures 112, to support a section 87 of phase conductor 102 (A).

The section 87 of conductor 102 (A) is mounted to the temporary dead endpole 113′, 113″ while the jumper cable 108 remains attached to the phaseconductor 102 (A), such that the power load on the phase conductor 102(A) continues to be transferred around the dead end juncture 110′, 110″by the jumper cables 108 while the section 87 of phase conductor 102 (A)is being relocated. FIG. 8 shows a first new phase conductor 114 (alsoreferred to as the D phase) strung into the original location 95 of theA phase conductor 102 (A). The first new phase conductor 114 becomes theD phase conductor, as the new phase conductor 114, with the exception ofany induced current caused by the surrounding current-carrying phases,initially does not carry any power load after being strung into place.

In many of the schematic diagrams of this patent specification,beginning with FIG. 8 , an ellipse or a circle is sometimes used tohighlight a feature illustrated in the schematic diagram that has beenadded or which has changed from the immediately preceding Figure. Forexample, FIG. 8 shows an ellipse around the new phase conductor 114strung into the original location 95 of the A phase conductor 102 (A),which is a new feature not illustrated in the immediately preceding FIG.7 . It is understood that such ellipses and circles are merely includedto clearly illustrate the changes that occur in the sequential steps ofa preferred embodiment of the present method invention described herein,and are not themselves representing features of the power transfersystem 100.

Once the new phase conductor 114 is in place, the power load istransferred from an adjacent phase conductor 102 to the new D phaseconductor 114. In the example illustrated in FIGS. 9-20 , the B phaseload in conductor 102 (B) will be transferred to the D phase conductor114. One way to accomplish the power transfer is with a temporarytransfer bus 118′, 118″.

FIG. 43 shows a preferred embodiment of a temporary transfer bus 118constructed of substantially rigid conductors 120, 120, an insulator 94located between the two conductors 120, 120, arranged in a substantiallyco-linear relationship with respect to the conductors 120, 120, busclamps 123, 123 and a plurality of connectors 121 for temporarilyattaching a jumper cable 108 or other conductor to one of the conductors120 of the transfer bus 118. Each of the conductors 120 of the transferbus 118 are attached to a tangent insulator 116 by means of a bus clamp123. Each tangent insulator 116 is suspended from either an existingphase conductor 102 or a new phase conductor 114. Once the temporarytransfer bus 118 is in place, there is no electrical connection betweenthe rigid conductors 120 of the transfer bus 118 due to the interveningtransfer bus insulator 94. An electrical connection may be establishedacross the insulator 94 of the transfer bus 118 by means of a jumpercable 108 attached to one or more of a plurality of connectors 121located on each of the rigid conductors 120. Optionally, and as furtherdiscussed below and illustrated in FIG. 43 , the electrical connectionacross the insulator 94 of the transfer bus 118 may also be establishedby means of a switch 140 (illustrated in FIGS. 44 and 45 ) orpreferably, a breaker 142, whereby jumper cables 148, 150 are used toconnect each of the first and second bushings, 144, 146 of the breaker142 to the first and second rigid conductors 120, 120 respectively ofthe transfer bus 118.

As mentioned above, care must be taken when connecting or disconnectingan energized conductor from another conductor in high voltageapplications such as the voltages associated with high voltage powerlines, because when the conductors are near each other, either beforeconnection or after the disconnection, a large potential will existbetween the energized conductor and the non-energized conductor. Due tothe large electrical potential between the conductors, large arcs canform between the conductors if the difference in potential is highenough.

Thus, there are three options for establishing and breaking anelectrical connection between the rigid conductors 120 of the transferbus 118 across the insulator 94. First, live line equipment such as hotsticks may be used to physically connect each end of a jumper cable 108to a conductor 120 of the transfer bus 118, as illustrated in FIG. 48 .Second, a conductor including a switch 140 may be connected to eachconductor 120 of the transfer bus 118. The switch 140 will initially beset in the open position before the connection of the switch to eachconductor 120 of the transfer bus 118 is made, and each conductor 120 ofthe transfer bus 118 may then be connected to a phase conductor 102 ornew phase conductor 114 using jumper cables 134 (see FIGS. 9 and 9 a)and hot sticks. Once each of the two conductors 120, 120 of the transferbus 118 are electrically connected to either the phase conductor 102 orphase conductor 114, the switch 140 may be closed to establish theelectrical connection between the two conductors 102, 114. Similarly,the third option of establishing an electrical connection between twoconductors 120, 120 across the insulator 94 of a transfer bus 118 issimilar to the second option described above, except that a breaker 142is used in place of the switch, as shown in FIG. 43 , and will not berepeated here.

Which method to use, the hot sticks and jumper cable, the switch or thebreaker depends on several factors. Two factors to consider are theelectrical potential between the conductors to be connected and the massof the non-energized conductor that is to be connected to the energizedconductor across the transfer bus 118. If the mass of the conductor tobe connected and/or the voltage potential is relatively minor, the twoconductors may be connected across the transfer bus by a jumper cable108 using hot sticks. As the mass of the conductor to be connected tothe energized conductor increases and/or the voltage difference betweenthe two conductors increases, a switch may be used to establish theelectrical connection across the insulator 94 of the transfer bus 118;finally, with conductors having a large mass and/or a large voltagepotential between the conductors, a breaker 142 is used to establish theconnection across the insulator 94 of the transfer bus 118. In thepreferred embodiment of the method described below, which is notintended to be limiting in any way, the electrical connection isestablished across the insulator 106 of the transfer bus 118 by means ofa breaker 142; however, it will be well understood by a personordinarily skilled in the art that the electrical connection may also beestablished across the insulator 94 of the transfer bus 118 by means ofa switch 140 or by means of a length of a conductor, such as for examplea jumper cable 108, depending on factors which include the electricalpotential and the mass of the non-energized conductor that is to beconnected to an energized conductor, as described above.

Once the D phase conductor 114 is in place, the power load istransferred from the conductor 102 (B) of the B phase line onto the Dphase conductor 114 over the course of several steps. FIG. 9 shows thatone rigid conductor 120 of a first transfer bus 118′ is electricallyconnected to the D phase conductor 114 by means of a jumper cable 134.FIG. 10 shows one rigid conductor 120 of a second transfer bus 118″ iselectrically connected to the D phase conductor 114 by means of a secondjumper cable 134. In FIGS. 9 and 10 , although it appears that the rigidconductors 120 of each of the transfer buses 118′, 118″ that areopposite of the rigid conductors 120 connected to the D phase conductor114 by means of the jumper cables 134, 134 are in close proximity to theB phase conductor 102 (B), there is no physical or electrical connectionbetween those rigid conductors 120 of the transfer buses 118′, 118″ andthe B phase conductor 102 (B), as the transfer buses 118, 118 arepositioned either above, or preferably, below the B phase conductor 102(B).

As illustrated in FIGS. 11 and 12 , once the breaker 142 of eachtransfer bus 118′, 118″ is confirmed to be set in the open position, ajumper cable 134 is used to electrically connect a rigid conductor 120of each transfer bus 118′, 118″ to a section 90 of the B phase conductor102 (B) located between two dead end junctures 110′, 110″. Asillustrated in FIG. 12 , once the first rigid conductors 120 of eachtransfer bus 118′, 118″ are each connected to the D phase conductor 114and the second rigid conductors 120 of each transfer bus 118′, 118″ areconnected to the B phase conductor 102 (B), the breaker 142 on eachtransfer bus 118′, 118″ remains in the open position and therefore the Dphase conductor 114 remains de-energized.

In FIG. 13 , the breaker 142 of transfer bus 118″ is closed, therebyestablishing an electrical connection between the energized B phaseconductor 102 (B) and the new phase conductor 114, whereby the new phaseconductor 114 is brought to the same voltage potential difference as theB phase conductor 102 (B). Because the new phase conductor 114 shown inFIG. 13 is connected to the B phase conductor 102 (B) at only onelocation, current is flowing only over the B phase conductor 102 (B) andnot over the new phase conductor 114. The new phase conductor 114 hasthe same electrical potential as the B phase conductor 102 (B), but thenew phase conductor 114 does not yet transport a power load.

In order for current to flow through the new phase conductor 114, thebreaker 142 of the transfer bus 118′ must be closed, as shown in FIG. 14. Once the breakers 142, 142 on each of the transfer buses 118′, 118″are closed, a parallel path is created for the B phase current to runthrough both the new phase conductor 114 and the original B phaseconductor 102 (B).

As illustrated in FIG. 15 , at one of the dead end juncture 110′ onopposite ends of section 90 of the original B phase conductor 102 (B),one end of a long jumper cable 111 is connected to a section 91 of theoriginal B phase conductor 102 (B) that is oppositely disposed on deadend juncture 110′, and the other end of the long jumper cable 111 isconnected to the new phase conductor 114, creating a parallel connectionfor the B phase current to flow around the dead end juncture 110′. Asshown in FIG. 16 , jumper cables 108, 108 are removed from around onedead end juncture 110′ on the B phase conductor 102 (B). The removal ofthe jumper cables 108, 108 can, if the voltage and/or the mass of theconductor 102 (B) is low enough, be removed by using hot sticks. If thevoltage and/or mass of the conductor 102 (B) are too high, other meansof breaking the connection around the dead end juncture 110′ may be usedwhich may include a switch or breaker described in greater detail above.

As shown in FIG. 17 , at the second dead end juncture 110″ on theopposite end of the section 90 of the original B phase conductor 102(B), one end of a long jumper cable 111 is connected to a section (orotherwise referred to as a “segment”) 92 of the B phase conductor 102(B) that is oppositely disposed of dead end juncture 110″, and the otherend of the long jumper cable 111 is connected to the new phase conductor114, creating a parallel connection for the B phase current to flowaround the second dead end juncture 110″. As shown in FIG. 18 , jumpercables 108, 108 are removed from around the second dead end juncture110″ of the original B phase conductor 102 (B).

In FIG. 19 , the breaker 142 of transfer bus 118′ is opened. The effectof opening one breaker 142 is that the current no longer flows throughthe section 90 of the original B phase conductor located between thedead end junctures 110′, 110″. All of the B phase current now flowsthrough the new conductor 114 rather than the original B phase conductor102 (B). However, because the breaker 142 of the other transfer bus 118″remains closed, an electrical connection still exists between theoriginal B phase conductor 102 (B) and the new conductor 114 at onepoint; therefore, the electrical potential between the original B phaseconductor 102 (B) and the new phase conductor 114 remains the same.

To electrically isolate the section 90 of the original B phase conductor102, the breaker 142 of the second transfer bus 118″ is opened, as shownin FIG. 20 . In other embodiments of the present invention, if thevoltage and/or the mass of the original B phase conductor 102 is lowenough, either a switch or a jumper cable may be substituted for thebreaker 142 to establish and break the electrical connection between therigid conductors 120, 120 of the transfer bus 118″. Upon opening thesecond transfer bus 118″, section 90 of the original B phase conductorbecomes electrically isolated from the system (except for currents whichmay be induced in section 90 of phase conductor 102 due to theelectromagnetic effects of the surrounding current-carrying phaseconductors), and the original B phase conductor therefore becomes the Dphase conductor, as it no longer carries the B phase current or anyphase current of the power transfer system 100.

One of the jumper cables 134 connecting a first end of the transfer bus118″ to the new B phase conductor 114 is removed, de-energizing the openbreaker 142. The second jumper cable 134 connecting a second end of thetransfer bus 118″ to the original B phase conductor 102 (which is nowde-energized and therefore has become the D phase conductor 102) is alsoremoved, and the temporary transfer bus 118″ is then removed from thepower transfer system 100, as illustrated in FIG. 21 . Similarly, thetwo jumper cables 134, 134 connecting the transfer bus 118′ at the firstend to the new B phase conductor 114 and at the second end to the Dphase conductor 102 are removed, and then the transfer bus 118′ isremoved from the power transfer system 100, as shown in FIG. 22 .

The section 90 of the D phase conductor 102 between the dead endjunctures 110′, 110″ is now isolated from all B phase potential by bothdead end junctures 110′, 110″. All current formerly carried by the Dphase conductor 102 now travels through the new B phase conductor 114.It is important to note that section 90 of the D phase conductor 102,now isolated from the system 100 power load, is not void of potential.The isolated section 90 of the D phase conductor 102 is, and should betreated as, a live conductor, because the isolated section 90 of the Dphase conductor 102 is subject to induced currents caused by thesurrounding current-carrying phase conductors 102, 114 and may stillhave a large potential with respect to ground.

At this stage in the procedure, the isolated section 90 of the originalB phase conductor may be broken down, worked on, or replaced withoutdisrupting downstream power delivery. For example, as illustrated inFIG. 23 , the section 90 of the original B phase conductor 102 isremoved and a second new phase conductor 115 is strung, sagged, deadended and clipped into the position of the original B phase conductor102. In some embodiments of the invention, the original B phase line 102is not removed but is rather worked on in other ways, such as replacingan insulator 106. One skilled in the art can appreciate that other typesof work may be done on the isolated section 90 of the B phase conductor102 in accordance with the invention.

The above describes the procedure, illustrated in FIGS. 1-23 , formoving the A phase conductor 102 (A) to a temporary location 96,stringing a first new phase conductor 114 in or near the originallocation 95 of the A phase conductor 102 (A), transferring the powerload from the B phase conductor 102 (B) to the D phase conductor 114,electrically isolating the section 90 of the B phase conductor 102 (B)located between two dead end junctures 110′, 110″ from the powertransfer system 100, and replacing the electrically isolated section 90of the B phase conductor 102 with a second new phase conductor 115. Theprocedure for transferring the power load from the C phase conductor 102(C) to the new D phase conductor 115 in accordance with the invention,described below and illustrated in FIGS. 24-28 , is similar to theprocedure for transferring the power load from the B phase conductor 102(B) to the new phase conductor 114 described above.

As shown in FIG. 24 , a section 97 of the C phase conductor 102 (C),located between two dead end junctures 110′, 110″ requires replacementor other maintenance or repair work. A first transfer bus 118′, with abreaker 142 connected to each of the two rigid conductors 120 of thetransfer bus 118, is connected at one end to the D phase conductor 115with a jumper cable 134, and the opposite end of the first transfer bus118′ is connected to the section 97 of the C phase conductor 102 (C)with a second jumper cable 134. A second transfer bus 118″ with abreaker 142 connected to each of the two rigid conductors 120 of thetransfer bus 118″, is connected at one end to the D phase conductor 115with a third jumper cable 134, and the opposite end of the secondtransfer bus 118″ is connected to the section 97 of the C phaseconductor 102 (C) with a fourth jumper cable 134. The electricalconnections described above between the transfer buses 118′, 118″ andthe phase conductors 115, 102 (C) are established after first checkingto confirm that the breaker 142 attached to each transfer bus 118′, 118″is open.

The breaker 142 attached to the first transfer bus 118′ is closed,thereby energizing the new phase conductor 115 at the same electricalpotential as the C phase conductor 102 (C). However, because anelectrical connection between the new D phase conductor 115 and the Cphase conductor 102 (C) has only been established through the firsttransfer bus 118′, although the new phase conductor 115 is energized itdoes not carry any current. The breaker 142 attached to the secondtransfer bus 118″ is then closed, bringing the new phase conductor 115in parallel with the C phase conductor 102 (C). Upon closing thebreakers 142, 142 on each of the transfer buses 118′, 118″, the C phasecurrent runs in parallel on both the new phase conductor 115 and the Cphase conductor 102 (C), as illustrated in FIG. 25 .

Once the C phase current is carried in parallel over the new phaseconductor 115 and the original C phase conductor 102 (C), the section 97of the original C phase conductor 102 (C) located between two dead endjunctures 110′, 110″ is electrically isolated from the power transfersystem 100. As shown in FIG. 26 , at the first dead end juncture 110′ afirst long jumper cable 111 is connected at a first end to a firstsection 98 of the original C phase conductor 102 (C) extending from thefirst dead end juncture 110′ oppositely to section 97, and a second endof the first long jumper cable 111 is connected to the new phaseconductor 115, establishing a parallel path around the first dead endjuncture 110′ for the C phase current to flow. Similarly, at the seconddead end juncture 110″ a second long jumper cable 111 is connected at afirst end to a second section 99 of the original C phase conductor 102(C) extending from the second dead end juncture 110″ oppositely tosection 97, and a second end of the second long jumper cable 111 isconnected to the new phase conductor 115, establishing a parallel patharound the second dead end juncture 110″ for the C phase current.

The breaker 142 connected to the first transfer bus 118′ is opened,breaking the parallel circuit between the original C phase conductor 102and the new phase conductor 115. However, the section 97 of the originalC phase conductor 102 remains at the same electrical potential as thenew phase conductor 115 until the breaker 142 connected to the secondtransfer bus 118″ is opened, as illustrated in FIG. 27 . When each ofthe breakers 142, 142 connected to the transfer buses 118′, 118″ areopen, the section 97 of the original C phase conductor 102 iselectrically isolated from the new C phase conductor 115 and becomes theD phase conductor. Although the D phase conductor 102 is de-energized atthis stage of the reconductoring or maintenance procedure, it is againimportant to note that section 97 of the original C phase conductor 102,while isolated from the system 100 power load, is not void of potential.The isolated section 97 of the original C phase conductor 102 is, andshould be treated as, a live conductor, because the isolated section 97of the original C phase conductor 102 is subject to induced currentscaused by the surrounding current-carrying phase conductors 102 (C),115, 114 and may still have a large potential with respect to ground.

The isolated section 97 of the original C phase conductor 102 may bebroken down, worked on, or replaced without disrupting downstream powerdelivery. For example, as illustrated in FIG. 28 , the two transferbuses 118′, 118″ are removed, section 97 of the original C phaseconductor 102 is removed, and a third new phase conductor 117 is strung,sagged, dead ended and clipped into the position of the original C phaseconductor 102. In some embodiments of the invention, the original Cphase line 102 is not removed but is rather worked on in other ways,such as replacing an insulator 106. One skilled in the art willappreciate that other types of work may be done on the isolated section97 of the phase conductor 102 within the scope of the invention.

Once the reconductoring, maintenance and/or repair work is completed onthe sections of the A, B and C phase conductors located between the deadend junctures 110′, 110″, the power load may be transferred toconductors located in the originating positions of the A, B and C phaseconductors, as described below and illustrated in FIGS. 29-42 .

As illustrated in FIG. 29 , a first transfer bus 118′ attached to anopen breaker 142 is connected at a first end of the transfer bus 118′ tothe new D phase conductor 117 using a jumper cable 134, and a second endof the transfer bus 118′ is connected to the new phase conductor 115using a second jumper cable 134. A second transfer bus 118″ attached toan open breaker 142 is connected at a first end of the transfer bus 118″to the new D phase conductor 117 using a third jumper cable 134, and asecond end of the second transfer bus 118″ is connected to the C phaseconductor 115 using a fourth jumper cable 134.

As illustrated in FIG. 30 , the breaker 142 attached to the firsttransfer bus 118′ is then closed, thereby energizing the new D phaseconductor 117 and bringing the new D phase conductor 117 to the sameelectrical potential as the C phase conductor 115. The breaker 142attached to the second transfer bus 118″ is closed, thereby bringing thenew D phase conductor 117 into parallel with the C phase conductor 115,whereby the C phase current flows through both the C phase conductor 115and the D phase conductor 117, as shown in FIG. 30 .

Next, as illustrated in FIG. 31 , two jumper cables 108, 108 are used toconnect the section 98 of the original C phase conductor 102 (C)opposite the new phase conductor 117 across the first dead end juncture110′ to the new phase conductor 117. Two additional jumper cables 108,108 are used to connect the section 99 of the original C phase conductor102 (C) opposite the new phase conductor 117 across the second dead endjuncture 110″ to the new C phase conductor 117 across the second deadend juncture 110″. Once the permanent jumper cables 108 are in place,the temporary long jumper cables 111, 111 connecting each of thesections 98, 99 of the original C phase conductor 102 to the C phaseconductor 115 are removed. The connection of the jumper cables 108 andthe disconnection of the temporary long jumper cables 111 isaccomplished using live line equipment, such as hot sticks. Once thisjumpering procedure is complete, whereby the new permanent jumper cables108 are installed and the temporary long jumper cables 111 are removed,the C phase current continues to flow in parallel through both the new Cphase conductor 117 and the phase conductor 115, through the circuitpath provided by the closed breakers 142 on the two temporary transferbuses 118′, 118″ as shown in FIG. 31 .

The breaker 142 connected to the first transfer bus 118′ is then opened,thereby breaking the parallel circuit between the new C phase conductor117 and the phase conductor 115. However, the phase conductor 115remains energized and at the same electrical potential as the new Cphase conductor 117. The breaker 142 connected to the second transferbus 118″ is then opened, thereby de-energizing the phase conductor 115,which becomes the D phase conductor because the phase conductor 115 nolonger carries the C phase current, or any phase current, as illustratedin FIG. 32 . At this stage, the two temporary transfer buses 118′, 118″may be removed from the power transfer system 100. Although the phaseconductor 115 is de-energized and is not carrying current at this pointin the reconductoring procedure, it must still be treated as a liveconductor because the isolated D phase conductor 115 is subject toinduced currents caused by the surrounding current-carrying phaseconductors 114, 117 and may still have a large potential with respect toground.

As illustrated in FIG. 33 , two temporary transfer buses 118′, 118″connected to breakers 142, 142 set in the open position are temporarilyinstalled between the D phase conductor 115 and the B phase conductor114, by utilizing jumper cables 134 to firstly connect a first end ofeach transfer bus 118′, 118″ to the D phase conductor 115 near each ofthe dead end junctures 110′, 110″, and then secondly using jumper cables134 to connect a second end of each transfer bus 118′, 118″ to the Bphase conductor 114 near each of the dead end junctures 110′, 110″. Oncethe temporary transfer buses 118′, 118″ are installed with the breakers142, 142 remaining open, the B phase current continues to flow throughthe sections 91, 92 of the original B phase conductor 102 (B) oppositeof the D phase conductor 115 on opposing sides of the dead end junctures110′, 110″ and through the B phase conductor 114. As such, the B phasecurrent continues to bypass the D phase conductor 115 while the breakers142, 142 remain open.

The breaker 142 connected to the first temporary transfer bus 118′ isclosed, energizing the D phase conductor 115 and bringing the phaseconductor 115 to the same electrical potential difference as the B phaseconductor 114. The breaker 142 connected to the second temporarytransfer bus 118″ is closed, thereby providing a parallel path for the Bphase current to flow through both the phase conductors 114 and 115, asillustrated in FIG. 34 . Once each of the two breakers 142, 142connected to the two transfer buses 118′, 118″ are closed, the B phasecurrent flows through the section 91 of the original B phase conductor102 (B) opposite the new phase conductor 115 across the first dead endjuncture 110′, through the long jumper cable 111 to the B phaseconductor 114, through the temporary transfer buses 118′, 118″ and theclosed breakers 142, 142 to the new B phase conductor 115, and throughthe second long jumper cable 111 to the section 92 of the original Bphase conductor 102 (B) located opposite the new phase conductor 115across the second dead end juncture 110″.

As illustrated in FIG. 35 , two jumper cables 108, 108 are used toconnect the section 91 of the original B phase conductor 102 (B)opposite the new phase conductor 115 across the first dead end juncture110′ to the new B phase conductor 115. Two additional jumper cables 108,108 are used to connect the section 92 of the original B phase conductor102 (B) opposite the new phase conductor 115 across the second dead endjuncture 110″ to the new phase conductor 115. Once the permanent jumpercables 108 are in place, the temporary long jumper cables 111, 111connecting each of the sections 91, 92 of the original B phase conductor102 (B) to the new B phase conductor 115 are removed. The connection ofthe jumper cables 108 and the disconnection of the temporary long jumpercables 111 is accomplished using live line equipment, such as hotsticks. Once this jumpering procedure is complete, whereby the newpermanent jumper cables 108 are installed and the temporary long jumpercables 111, 111 are removed, the B phase current continues to flow inparallel through both the new B phase conductor 115 and the B phaseconductor 114, through the path provided by the closed breakers 142, 142connected to each of the two temporary transfer buses 118′, 118″, shownin FIG. 35 .

The breaker 142 connected to the first transfer bus 118′ is then opened,thereby breaking the parallel circuit between the new B phase conductor115 and the phase conductor 114. However, the phase conductor 114remains energized and at the same electrical potential as the new Bphase conductor 115 once only one of the breakers 142 connected to thetransfer buses 1181, 118″ has been opened. The breaker 142 connected tothe second transfer bus 118″ is then opened, thereby de-energizing thephase conductor 114, which becomes the D phase conductor because thephase conductor 114 no longer carries the B phase current, as shown inFIG. 36 . At this stage, the two temporary transfer buses 118′, 118″ maybe removed from the power transfer system 100. Although the phaseconductor 114 is de-energized and is not carrying current at this pointin the reconductoring procedure, it must still be treated as a liveconductor because the electrically isolated phase conductor 114 issubject to induced currents caused by the surrounding current-carryingphase conductors 115, 102 (A) and may still have a large potential withrespect to ground.

As illustrated in FIG. 37 , a first transfer bus 118′ connected to anopen breaker 142 is connected at one end of the transfer bus 118′ to theD phase conductor 114 using a jumper cable 134, and a second end of thefirst transfer bus 118′ is connected to the original A phase conductor102 (A) using a second jumper cable 134. A second transfer bus 118″connected to an open breaker 142 is connected at a first end of thetransfer bus 118″ to the D phase conductor 114 using a third jumpercable 134, and a second end of the second transfer bus 118″ is connectedto the original A phase conductor 102 (A) using a fourth jumper cable134.

The breaker 142 connected to the first transfer bus 118′ is then closed,thereby energizing the D phase conductor 114 and bringing the D phaseconductor 114 to the same electrical potential as the original A phaseconductor 102 (A). The breaker 142 connected to the second transfer bus118″ is closed, thereby bringing the new phase conductor 114 intoparallel with the original A phase conductor 102 (A), whereby the Aphase current flows through both the original A phase conductor 102 (A)and the new A phase conductor 114, as shown in FIG. 38 .

As illustrated in FIG. 39 , two jumper cables 108, 108 are used toconnect the section 88 of the original A phase conductor 102 (A) locatedopposite the new A phase conductor 114 across the first dead endjuncture 110′ to the new A phase conductor 114. Two additional jumpercables 108, 108 are used to connect the section 89 of the original Aphase conductor 102 (A) located opposite the new A phase conductor 114across the second dead end juncture 110″ to the new A phase conductor114. Once the permanent jumper cables 108 are in place, the temporarylong jumper cables 111, 111 connecting each of the sections 88, 89 ofthe original A phase conductor 102 (A) to the new A phase conductor 114are removed. The connection of the jumper cables 108 and thedisconnection of the temporary long jumper cables 111 is accomplishedusing live line equipment, such as hot sticks.

Once this jumpering procedure is complete, whereby the new permanentjumper cables 108 are installed and the temporary long jumper cables 111are removed, the A phase current continues to flow in parallel throughboth the new A phase conductor 114 and the original A phase conductor102 (A), through the path provided by the closed breakers 142 connectedto each of the two temporary transfer buses 118′, 118″ as shown in FIG.39 .

The breaker 142 connected to the first transfer bus 118′ is then opened,thereby breaking the parallel circuit between the new A phase conductor114 and the original A phase conductor 102 (A). However, the original Aphase conductor 102 remains energized and at the same electricalpotential as the new A phase conductor 114. The breaker 142 connected tothe second transfer bus 118″ is then opened, thereby de-energizing theoriginal A phase conductor 102 (A), which becomes the D phase conductorbecause the original A phase conductor 102 (A) no longer carries the Aphase current or any other current, as illustrated in FIG. 40 .

At this stage, the two temporary transfer buses 118′, 118″ and thebreakers 142, 142 connected to the transfer buses 118′, 118″ may beremoved from the power transfer system 100, as illustrated in FIG. 41 .Although the original A phase conductor 102 (A), which is de-energizedand is not carrying current at this point in the reconductoringprocedure and has therefore become the D phase, it must still be treatedas a live conductor because the electrically isolated phase conductor102 is subject to induced currents caused by the surroundingcurrent-carrying phase conductor 114 and may still have a largepotential with respect to ground. As shown in FIG. 42 , the original Aphase conductor 102 (A) may be removed from the temporary supportstructures 112, 112; optionally, the temporary support structures 112may also be removed from the power transfer system 100.

As a person ordinarily skilled in the art will appreciate, the improvedmethod for conducting repairs and maintenance on live conductorsdescribed herein provides the ability to replace, maintain or repair oneor more phase conductors without interrupting the supply of power todownstream customers by relocating a section of a phase conductorlocated between two dead end junctures to a temporary location,transferring the power load from a section of an adjacent conductorlocated between two dead end junctures to the temporarily relocatedconductor, performing maintenance or repair work on the adjacentconductor, or in the alternative, replacing the adjacent conductor witha new conductor, and then repeating the steps of transferring powerloads and conducting repair, maintenance or replacement on each adjacentconductor until all of the desired repair, maintenance or replacementwork is complete.

Importantly, this improved method described herein enables repair,maintenance or replacement work to be conducted on live conductors whileavoiding the illegal transposition of the phase conductors throughoutthe entire procedure. Because of the effect of induced currents andimpedance on a phase conductor caused by the close proximity ofadditional live phase conductors, it is possible that transposing onephase conductor with respect to the other phase conductors may result inan electrical surge in one or more of the phase conductors, which inturn may trip a protective relay and result in the disruption of powerdelivery to downstream customers.

By way of illustrating an example of illegal transposition, considerthree phase conductors carrying phases A, B and C that are arrangedhorizontally with respect to each other in the following order: A-B-C.In the method described herein, as illustrated in FIGS. 1-42 , therelative position of each of the phase conductors, “A-B-C”, remains thesame at each step of the re-conductoring procedure. In other words, atno point during the procedure described herein does the relativepositions of the A, B and C phase conductors change from the originalA-B-C relative arrangement; that is, at no point in the exampleillustrated and described herein does the method result in transpositionof the phase conductors to, for example, an A-C-B arrangement or a C-A-Barrangement or any other transposed arrangement.

Furthermore, in the example of the procedure described herein andillustrated in FIGS. 1-42 (see in particular, FIGS. 4 and 5 ), the Aphase conductor 102 is relocated to temporary position 96 at a distanceL from the originating position 95 of the A phase conductor 102, whereinthe distance L is substantially equal to the phase spacing distance Jbetween C phase conductor 102 and B phase conductor 102, and L is alsosubstantially equal to the phase spacing distance J between B phaseconductor 102 and the originating position 95 of the A phase conductor102. Temporarily relocating A phase conductor 102 to a temporaryposition 96 at a distance L from the originating position 95 that issubstantially equal to the existing phase spacing J between the A, B andC phase conductors minimizes the induced current and resulting impact onthe impedance on the phase conductors A, B and C that may otherwiseoccur if distance L was substantially shorter or longer than phasespacing J, and/or if the positions of any of the phase conductors A, Band C were to be transposed from their original A-B-C relativepositioning at any point during the maintenance and repair workdescribed herein.

An example of a procedure for stringing a de-energized, new phaseconductor into a transmission system, such as for example the D phaseconductor 114 illustrated in FIG. 8 , involves connecting a traveler toa support structure, stringing a pull line (or pulling line) with atleast one non-conductive end through the traveler, connecting the pullline via a swivel and a flexible isolator to the conductor, pulling thepull line through the traveler and thereby causing the conductor to bestrung through the traveler, attaching the conductor to the supportstructure, removing the traveler from the support structure, anddisconnecting the pull line from the conductor. It is known by a personordinarily skilled in the art to use a di-electric tested section ofrope installed between the pulling line and the new conductor beingstrung onto the support structure to provide the non-conductive end ofthe pull line. The Applicant recently filed U.S. application Ser. No.14/664,724 filed on Mar. 20, 2015, entitled Flexible ElectricalIsolation Device, the disclosure of which is incorporated herein in itsentirety, describes a flexible elongated insulator having couplingsmounted at either end of the insulator. This isolation device, otherwisereferred to as a flexible isolator or flexible insulator, consists of aflexible, bendable or otherwise deformable (herein collectively referredto as flexible) member to accommodate the bending radius of a travelerand is composed of a high tensile strength, dielectric material withattachment points, or couplings, on each end. The attachment points orcouplings are constructed so as to control both rotation imparted by thecables and bi-directional shear induced when the couplings or attachmentpoints pass through the conductive travelers.

A switch 140 may be used in place of the breaker for lighterapplications. Operation using the switch in place of a breaker isbasically the same and will not be repeated. The switch 140 is a typicalair break disconnect switch. It has a disconnect blade 141 that can beoperated to a closed position (see FIG. 44 ) and an open position (seeFIG. 45 ). The switch 140 has connectors 145 on each end that permitsconductors 120, 120 of the transfer bus 118 to be electrically connectedto the switch 140. When the disconnect blade 141 is in the closedposition, it provides an electrical connection between the twoconductors 120, 120 via the switch 140. When the disconnect blade 141 isin the open position, there is no electric connection between the twoconductors 120, 120.

The switch 140 has an actuator 143 that operates the disconnect blade141. The opening and closing of the switch is controlled by the actuator143. The switch 140 is supported on a frame 147 that provides mechanicalsupport for the switch 140. The frame 147 is insulated from theconductors by insulators 149. According to some embodiments of theinvention, the switch 140 may be mounted on temporary support structureor a lift apparatus, such as a boom of a vehicle or, for example,preferably a robotic mechanical arm device 101 adapted to manipulateheavy energized conductors such as the phase conductors 102 described inthe Applicant's U.S. Pat. No. 8,573,562, for ease and convenience inpracticing some embodiments of the invention.

The breaker 142 shown schematically in FIGS. 9-40 and 43 will now befurther illustrated and described with reference to FIG. 46 . In someembodiments of the invention, the breaker 142 is a single pole (phase)of a 345 kV breaker that has been modified to be portable. A typicalbreaker of this magnitude consists of three single pole breakersmechanically connected together to be a three phase breaker and breakall three circuits at once. The three phase breaker includes threebreakers connected together and configured to act in unison. Becauseonly a single phase needs to be disconnected or energized at once inmany embodiments of the invention, only one pole (or phase) of a breakeris needed. To make the breaker more portable, one pole is separated fromthe three phase unit and modified to be portable as described in moredetail below.

A breaker 142 in accordance with the invention may be, as an example notintending to be limiting, a 2,000 amp SF₆ breaker wherein SF₆ is aninsulating gas that is used in the breaker 142. In other embodiments ofthe invention, the breaker 142 could be a minimum oil breaker, or anyother breaker suited to the applied voltage. The breaker 142 has twoinsulated bushings 144, 146 projecting from a housing 156. Jumpers 148,150 are attached to an end of the bushings 144, 146 for connecting thebreaker 142 to conductors.

The breaker 142 has a closed position that permits an electricalconnection from a conductor connected to one bushing 144 via jumper 148through the breaker 142 to a conductor connected to the other bushing146 via jumper 150. When it is desired to break the electricalconnection between the two conductors 120, 120 of the transfer bus 118,the breaker 142 is operated to achieve an open position. In the openposition, the two jumpers 148, 150 connected to the two bushings 144,146 are isolated from each other.

Normally, a breaker 142 having the capacity for high voltage power islocated in fixed locations, such as for example power generatingfaculties, terminals, switching stations or substations, and consists ofthree poles or phases. In accordance with the invention, a standardbreaker 142, such as a 345 kilovolt, 2,000 amp SF₆ breaker, is used.Because these types of breakers have three poles or phases, a singlepole or phase is separated out from the other two phases and is modifiedso as to be portable. As shown in FIG. 46 , the breaker 142 is mountedonto a trailer 158. A support structure 160 mounts the breaker 142 tothe trailer 158. Optionally, the breaker 142 could be mounted on a truckbed or some other suitable type of vehicle.

The breaker 142 has a housing 156 from which two insulated bushings 144,146 project. One of the bushings 144 is located on what is referred toas the line side 162, meaning that that bushing 144 connects to theconductor, for example phase conductor 102, that is connected to a powersource. The other side 164 of the breaker 142 is referred to as the loadside 164 and includes the other bushing 146. Within the housing 156 anon-conductive gas, SF₆ for example, is used for electrical insulation.Other breakers in accordance with the invention may be oil-filledbreakers or other types of breakers suitable for the applied voltage.

A control panel 166 for operating the breaker 142 is located on thetrailer 158 and operatively connected to the breaker 142. Optionally,the control panel 166 may be the same one that would normally operate astandard non-portable breaker. A portable power generator 168 is locatedon the trailer 158 and is operatively connected to the breaker 142and/or control panel 166 to provide power to operate the breaker 142.The generator 168 may be gasoline powered and is of sufficient capacityto permit operation of the breaker 142, including charging of thesprings in the breaker 142. Preferably, the generator 168 can produce120 volts.

Additional containers 170 of SF₆ gas are kept on the trailer 158 inorder to permit recharging of the breaker 142 with gas if necessary. Themanufacturer's recommendations for gas pressure in the breaker 142should be observed.

The exact modifications necessary to make the breaker 142 portable willvary depending on the type of breaker is being modified. A personordinarily skilled in the art after reviewing this disclosure will beable to appropriately fashion a portable breaker 142.

Before use of the breaker 142, the tow vehicle is detached and thetrailer 158 is held in place by jacks 172 and a wheel chocks 174. Thetrailer 158 and the breaker 142 is bonded to ground with groundingcables 176. A temporary protective fence 178 is constructed around thetrailer 158.

FIGS. 49 to 56 depict a method of replacing energized high-voltage powertransmission conductors while they remain energized.

FIG. 49 is a front, elevation view of a schematic of a support structure104 that is supporting three phases of conductors 102A, 102B and 102C byinsulators 116. Each of the conductors 102A, 102B and 102C carry anelectrical load. The A phase conductor 102 A is positioned on thesupport structure 104 in a first conductor position 400. The B phaseconductor 102B is positioned on the support structure 104 in a secondconductor position 402. The C phase conductor 102C is positioned on thesupport structure 104 in a third conductor position 404. Theconfiguration of the support structure 104 depicted in FIGS. 49 to 56and, in particular the first, second and third conductor positions 400,402, 404 may be in different positions upon the support structure 104and the positions depicted are not intended to be limiting. While thefirst, second and third conductor positions 400, 402, 404 are depictedas being in one single, horizontal plane, these positions can be in asingle plane that is not horizontal, for example it may be substantiallyvertical or between a horizontal plane and a vertical plane or may notbe in a single plane at all. The ordered sequence of the three phases ofconductors 102A, 102B and 102C is maintained with the conductor 102Aadjacent conductor 102B but not adjacent conductor 102C. Conductor 102Bis adjacent, or in between, both of conductor 102A and conductor 102C.

FIG. 50 depicts a step of installing, providing, or using an existingtemporary structure 112 along side the support structure 104. In thisexample, the temporary structure 112 provides a fourth conductorposition 406. The C phase conductor 102C is transferred in step 200 fromthe support structure 104 to the fourth conductor position 406 on thetemporary structure 112. A first replacement conductor 300 is strung into the position on the support structure 104 where the C phase conductor102C was located, in other words at the third conductor position 404.

FIG. 51 depicts a transferring step 202 wherein the electrical load ofthe B phase conductor 102B is transferred to the first replacementconductor 300 in the third conductor position 404. The B phase conductor102B is replaced by a second replacement conductor 302. At this step inthis method, the electrical load of the C phase conductor 102C iscarried through the C phase conductor 102C, which is supported on thefourth conductor position 406 by the temporary structure 112. Theelectrical load of the B phase conductor 102B is carried through thefirst replacement conductor 300 in the third conductor position 404.

FIG. 52 depicts transferring step 204 wherein the electrical load of theA phase conductor 102A is transferred to the second replacementconductor 302 in the second conductor position 402. The A phaseconductor 102A is the replaced by a third replacement conductor 304.

FIG. 53 depicts transferring step 206 wherein the electrical load on thesecond replacement conductor 302 is transferred to the third replacementconductor 304.

FIG. 54 depicts transferring step 208 wherein the electrical load on thefirst replacement conductor 300 is transferred to the second replacementconductor 302.

FIG. 55 depicts transferring step 210 wherein the electrical load fromthe C phase conductor 102C is transferred to the first replacementconductor 404.

During this method, the electrical load of the C phase is transferredfrom the third conductor position 404 to the fourth conductor position.The electrical load of the B phase is transferred from the secondconductor position 402 to the third conductor position 404. Theelectrical load of the A phase is transferred from the first conductorposition 400 to the second conductor position 402. Between each of thesetransfer steps, an old conductor is replaced with a new, replacementconductor wire. Then the steps are reversed with the electrical load ofthe A phase being transferred back to the first conductor position 400from the second conductor position 402, the electrical load of the Bphase being transferred back to the second conductor position 402 fromthe third conductor position 404, the electrical load of the C phasebeing transferred back to the third conductor position 404 from thefourth conductor position 406. In this fashion illegal transpositions ofthe A, B and C phases are avoided while the electrical loads of the A, Band C phases are returned to their original conductor positions, nowcarried through new conductor lines 300, 302, 304, as depicted in FIG.56 .

The various embodiments of the method of the invention described herein,temporarily relocating a phase conductor 102, stringing a D phaseconductor into place and using the D phase conductor to successively andin sequence transfer the electrical loads from proximate conductors,permits sections of new conductors, located between dead end junctures,to be strung one at a time. If it is desired to string new conductorsalong the entire length of a system 100, or a length longer thanpractical for stringing conductors, then the re-conductoring methods areused for lengths that are practical and repeated along the length of thesystem until a desired length of new conductor is installed along thesystem.

It is appreciated by one skilled in the art, that in some power transfersystems 100, more than one conductor 102 carries the power load for aparticular phase. This may be done in instances when a power load isgreater than a single-phase conductor can accommodate. In such cases,multiple (bundled) phase conductors 102 are often located next to eachother and may hang from the same insulator 116 as shown in FIG. 47 . Theconductors may be separated by spacers 198. Such bundle conductorsystems 100 may be re-conductored in accordance with the invention byapplication of the procedures described herein to each conductor 102.

While the above disclosure describes certain examples of the presentinvention, various changes, adaptations and modifications of thedescribed examples will also be apparent to those skilled in the art.The scope of the claims should not be limited by the examples providedabove; rather, the scope of the claims should be given the broadestinterpretation that is consistent with the disclosure as a whole.

1. A method for maintaining one or more sections of electricallyconductive phases in a DC two phase power system without interruptingpower in either of the two phases, the two DC phases denoted as A and Bphases, and wherein the two phases are parallel and are spaced apart,and wherein the A and B phases have corresponding A and B loads and atleast one of the A and B phases has a section needing maintenance, andthe A and B phases are strung between two support structures supportingthe two phases suspended above a ground, the method comprising steps of:(a) enabling a D phase located proximal to a phase needing maintenanceby methods chosen from: providing a new D phase in the DC two phasepower system adjacent the A phase when the A phase is the phase needingmaintenance or de-energizing a phase located proximal to the phaseneeding maintenance, while the A and B phases are strung, so that thephase located proximal to the phase needing maintenance becomes a Dphase, and wherein the step of providing the new D phase includes:providing an auxiliary support structure substantially adjacent the twosupport structures and proximal the A phase, moving the section of the Aphase needing maintenance to the auxiliary support structure, stringinga new D phase section between the two support structures where thesection of the A phase needing maintenance was moved from, and treatingthe new D phase section as an energized conductor; (b) paralleling withand transferring a power load carried by the phase needing maintenanceto the D phase by: (i) initiating transfer of the power load byestablishing a parallel electrical connection between the phase needingmaintenance and the D phase through a pair of jumpers extending inelectrical connection between the phase needing maintenance and the Dphase wherein the pair of jumpers do not cross over the other energizedphase in the DC two phase power system; and (ii) completing transfer ofthe power load to the D phase by de-energizing the phase needingmaintenance; and (c) maintaining the de-energized phase needingmaintenance while maintaining its position relative to the other phasein the DC two phase power system.
 2. The method of claim 1, wherein afirst lateral distance between the new D phase section and the sectionof the A phase needing maintenance supported on the auxiliary supportstructure is substantially no less than a phase-to-phase lateralseparation.
 3. The method of claim 1, wherein the section of the A phaseneeding maintenance strung on the auxiliary support structure issubstantially parallel to the new D phase section strung between the twosupport structures.
 4. The method of claim 1, wherein the stringing ofthe new D phase section further comprises the steps of: providing apulling line having at least one non-conductive end, connecting said atleast one non-conductive end of said pulling line to a leading end ofthe new D phase section, providing first and second equal potentialzones at opposite ends of a stringing path where along the new D phasesection is to be strung, wherein said first and second equal potentialzones are grounded, electrically connecting said pulling line to saidfirst equal potential zone, electrically connecting the new D phasesection to said second equal potential zone, electrically connectingpulling equipment at said first equal potential zone to said first equalpotential zone and electrically connecting pay-out equipment at saidsecond equal potential zone to said second equal potential zone, pullingsaid pulling line along said stringing path using said pulling andpayout equipment so as to pull said pulling line into said first equalpotential zone while paying-out the new D phase section along saidstringing path from said second equal potential zone.
 5. The method ofclaim 4, wherein said at least one non-conductive end of said pullingline is comprised of a flexible electrical isolator.
 6. A method formaintaining one or more sections of electrically conductive phases in aDC two phase power system without interrupting power in either of thetwo phases, the two DC phases denoted as A and B phases, and wherein thetwo phases are parallel and are spaced apart, and wherein the A and Bphases have corresponding A and B loads and at least one of the A and Bphases has a section needing maintenance, and the A and B phases arestrung between two support structures supporting the two phasessuspended above a ground, the method comprising steps of: (a) enabling aD phase located proximal to a phase needing maintenance by methodschosen from: providing a new D phase in the DC two phase power systemadjacent the A phase when the A phase is the phase needing maintenanceor de-energizing a phase located proximal to the phase needingmaintenance, while the A and B phases are strung, so that the phaselocated proximal to the phase needing maintenance becomes a D phase, andwherein the step of providing the new D phase includes: providing anauxiliary support structure substantially adjacent the two supportstructures and proximal the A phase, moving the section of the A phaseneeding maintenance to the auxiliary support structure, stringing a newD phase section between the two support structures where the section ofthe A phase needing maintenance was moved from, and treating the new Dphase section as an energized conductor, and wherein the step ofstringing of the new D phase section further comprises the steps of:providing a pulling line having at least one non-conductive end,connecting said at least one non-conductive end of said pulling line toa leading end of the new D phase section, providing first and secondequal potential zones at opposite ends of a stringing path wherealongthe new D phase section is to be strung, wherein said first and secondequal potential zones are grounded, electrically connecting said pullingline to said first equal potential zone, electrically connecting the newD phase section to said second equal potential zone, electricallyconnecting pulling equipment at said first equal potential zone to saidfirst equal potential zone and electrically connecting pay-out equipmentat said second equal potential zone to said second equal potential zone,pulling said pulling line along said stringing path using said pullingand payout equipment so as to pull said pulling line into said firstequal potential zone while paying-out the new D phase section along saidstringing path from said second equal potential zone; (b) parallelingwith and transferring a power load carried by the phase needingmaintenance to the D phase by: (i) initiating transfer of the power loadby establishing a parallel electrical connection between the phaseneeding maintenance and the D phase through a pair of jumpers extendingin electrical connection between the phase needing maintenance and the Dphase wherein the pair of jumpers do not cross over the other energizedphase in the DC two phase power system; and (ii) completing transfer ofthe power load to the D phase by de-energizing the phase needingmaintenance; and (c) maintaining the de-energized phase needingmaintenance while maintaining its position relative to the other phasein the DC two phase power system.
 7. The method of claim 6, wherein afirst lateral distance between the new D phase section and the sectionof the A phase needing maintenance supported on the auxiliary supportstructure is substantially no less than a phase-to-phase lateralseparation.
 8. The method of claim 6, wherein the section of the A phaseneeding maintenance strung on the auxiliary support structure issubstantially parallel to the new D phase section strung between the twosupport structures.
 9. The method of claim 6, wherein said at least onenon-conductive end of said pulling line is comprised of a flexibleelectrical isolator.